Civil Engineering Reference
In-Depth Information
TABLE 2.1
Summary of Plate Tectonics Theory
Plate
boundary
Type of plate
type
movement
Categories
Types of earthquakes
Examples
Earthquakes on spreading
ridges are limited to the
Relative
Seafloor spreading
ridge crest, where new crust
Mid-Atlantic
movement of
ridge (Fig. 2.3)
is being formed. These
ridge
Divergent
the two plates
earthquakes tend to be
boundary
is away from
relatively small and occur
each other.
at shallow depths.
Continental rift
Earthquakes generated
East African
valley (Fig. 2.4)
along normal faults in
rift
the rift valley.
1. Shallow interplate thrust
events caused by failure
of the interface between
Oceanic-continental
the down-going plate and
subduction zone
the overriding plate.
Peru-Chile
(Fig. 2.5)
trench
2. Shallow earthquakes
caused by deformation
within the upper plate.
3. Earthquakes at depths
Relative
from 25 to 430 mi (40
Convergent movement of
Oceanic-oceanic
to 700 km) within the
boundary
the two plates
subduction zone
down-going plate.
is toward each
(Fig. 2.6)
other.
4. Earthquakes that are
Aleutian
seaward of the trench,
Island chain
caused mainly by the
flexing of the down-going
plate, but also by
compression of the plate.
Continent-continent
Earthquakes generated at the
collision zone
collision zone, such as at
Himalaya
(Fig. 2.7)
reverse faults and thrust faults.
Mountains
Plates slide
past each other, Strike-slip fault
Earthquakes often generated
San Andreas
Transform
without the
zones (Fig. 2.9)
on strike-slip faults.
fault
boundary
construction or
destruction of
the earth's
crust.
